3 ms·

I thought it was also about removing the water vapor which could condense out in cold conditions.

• jandrewrogers 4y ago
  My limited knowledge comes from a former life where I was trained diesel mechanic for heavy machinery, and this was a specific part of our education. Cold weather was never a concern related to nitrogen. The scenario everyone worried about, and was beaten into our heads, was a bit of oil or grease leaking into the tires, which is pretty normal on heavy equipment. Under typical conditions, this is harmless. However, under high compression that oil can start to vaporize, which basically turns it into highly flammable fuel. Under the right conditions this fuel when mixed with the pressurized air can and will spontaneously combust. Failures can be pretty spectacular, and they had video to prove it. The nitrogen removes the oxygen from the equation so that the combustion can never occur. Apparently it happened often enough historically that it is mandatory practice in many domains. For me, this was received wisdom because I've never seen this kind of explosive failure in real life, which is a great thing. But if I put my chemical engineer hat on it also is eminently plausible, so I put it in the category of "lessons they learned the hard way".
  • LorenPechtel 4y ago
    I didn't know that scenario but I certainly could see it happening. Oxygen under enough pressure becomes a pretty nasty oxidizer. Especially when it happens suddenly. (Open the valve on a high pressure oxygen tank, pressurizing a system that wasn't previously pressurized.) By the time you add enough heat to the mix--rocket engines always run fuel-rich because at those temperatures an engine that runs oxygen rich probably then runs engine-rich. If you burn an engine to fuel exhaustion you likely destroy it.